Convolution and Filtering Raed S. Rasheed 2012

Convolution and Filtering Convolution is the fundamental neighborhood operations of image processing. Used for filtering of images e.g., to suppress noise or enhance edges.

Convolution In convolution, the calculation performed at a pixel is a weighted sum of grey levels from a neighborhood surrounding a pixel. The neighborhood includes the pixel under consideration, and it is customary for it to be disposed symmetrically about that pixel.

Convolution

Convolution

Convolution

Convolution Computational problems No processing at the border Copying of input image pixels Truncation of the image Truncation of the kernel

Filtering Mean & Median filter In which we select the middle-ranked value from a neighborhood as our output value. For a 3x3 neighborhood, the middle value is fifth in the list of sorted grey levels; for an nxn neighborhood with n odd, the middle value is at position n2/2 + 1.

Filtering

Filtering